Hello everyone,

Another electrical fault symptom I hope to get some clarity on. I've searched for similar topics but could not find a definitive answer.

Last autumn (2022) I had the somewhat common "start - no crank" situation. I did see in my, then limited, knowledge the starter as the culprit, being almost 30 years old. Turned out it was the false bulkhead connection on the right side which has been burned up pretty badly.

Changes have been made last autumn:
- NEW Denso Starter (OEM)
- Turbo Heatshield for the starter to prevent excessive heat absorption
- NEW Bulkhead Connector

The issue has been mostly resolved afterwards but it has still shown the same "no crank" symptom twice during the last exact one year. It won't crank upon starting but once key is put out and in again, everything works as it should. Today however it didn't crank for countless times. I did switch the battery off and on and the issue went away immediately. What could be the issue?

Additional information:
- The transmission can always be put out of PARK. This seems to be the issue with some other members' cars but not on mine.
- The car gets opened with the key fob. All buttons work, so the key gets recognized. This seems also to be possible fault on some cars.
- The car gets driven daily with countless stops a day, so no issues with sitting still for long periods of time.

Looking forward to some insight and I thank you for your time.

Greetings from Austria,
Oliver

 

Before you dig into the ignition switch, try cleaning the ground strap connections between the bell housing and frame, also the battery cable connections.

 

It sounds like a loose battery cable . .

 

I am with Jim on this. It sounds more like a poor connection somewhere
along the battery/starter route.

 

Take a peek at the gearshift indicator. Is the “P” glowing red? It should be…and the starter won’t operate if it isn’t.

On my XJR/6 this was solved by adjusting the linear switch on the RH side of the gearshift.

Cheers
DD

 

Oliver, just to be clear, is your car an X300 or an X308?

 

Hi guys,

thanks a ton for all the input! To answer a few things:

1.) The ground strap on the bell housing / frame is already new. Not even a year old and still looks superb.
2.) I am not sure about the battery. I have a "knob style" switch on one terminal for fast connecting/disconnecting the battery. Are there any more straps prone to failure?
3.) The gears are all illuminated depending on the lever position. Parking brake switch works as you can select any gear while the car has its "no starting situation".

The car is a November 1997 X308 XJR

Cheers,
Oliver

 

Battery cable failure is not so much an issue as poor connections due to corrosion. Disconnecting and cleaning the cables and straps is what's required.

 

Thank you all for the input! I have tried to clean up some of the connections which included:

- Engine bay left side (near the two fuse boxes)
- False bulkhead (has been new already)
- Transmission to frame (has been already new)
- cleaning of battery terminal cables

There also has been a well written electrical troubleshooting guide here on the forum by avt007 which I have followed. The battery voltage on the running car is 14.47V and the voltage on the high power protection module is 14.47V on all four studs as well which leads me to assume that there is no issue in my case.

I have ordered the following parts to be changed:

- Hood ground strap
- Battery terminal negative lead

The no start (no crank - just silence) symptom only occurs in summertime or warmer weather after the car has been driven and is still hot once restarting. So it must be connected to the heating of certain components. After the two leads above are changed I will also check the connection near the alternator which is apparently known to be a weak spot.

I will be back if this has eliminated the issue or not.

Cheers,
Oliver

 

There’s 3 circumstances (in my experience anyways) that I’ve encountered. 1) A customer had a new battery installed at parts store. Car started and he drove it 40 miles to another town. Once he turned the engine off, ALL signs of life from the car were gone. About an hour later he stated that he got back in the car and everything was normal again. He started it up and drove home with no issues. This went on for a certain number of weeks before he brought it in to us. After I checked the basics, I saw the sides of the battery were severely bowed out. I loosened the T40 bolts holding the battery hold down bar and they were more normal now. A much longer story short, that turned out to be the problem.

2) I know you have a new Denso starter so this may not be your issue. There was a member on here that was having a similar issue but different. He could start the car every morning or after several hours of not using the car. If he went to get gas, groceries, short stops, etc, the car would power up but the starter made no noise at all. Again, much longer story short, it was the starter. Once the starter heat soaked, the contacts inside the starter must’ve expanded away from each other to prevent any connectivity and once cooled, the contacts returned to normal so you can start the engine. The fix was a new starter for him.

3) I’ve encountered battery power and ground cables that gets really hot due to the braids forming high resistance either from corrosion or inside the crimp joints where you can’t clean them.

I’m sure there’s many other things that can take place such as modules or ignition switch, starter trigger wire near the exhaust, starter relay, etc.

Swap the starter relay with an unimportant one like rear fog lights from the trunk.

 

There's also the (faulty) temp sensor that can create a no crank, along with the engine to chassis earth strap underneath the car.

 

Good points! Thank you.

1) The battery could be an issue, yet I do think it is unlikely in my case but well worth keeping in mind.

2) Absoluetely! I have read about that too. Therefore, I have wrapped the starter with a heat shield that heat soak is not an issue anymore. I would rule out this possibility completely.

3) This might be our best guess, especially because some braids look solid but might not be. I will change a few more braids and will report back

 

Sean, you mean a faulty coolant temp sensor? This one I already changed to an OEM new one.

The chassis strap is also brand new.